How can I move the generated artifacts after generation?

I want to move the generated artifacts after generation, e.g. for renaming xml files or to move all of them into a custom folder or special subfolder.
I can't really find a simple way to do this. Should I do this in a post-processing script? Or is a custom facet the way to go? In both cases: are there any examples on how to do this? (The sampleFacet sample project that comes with MPS 3.1.3 is broken for me).

Thanks in advance for any help or tipps. Cheers,
Arne